This study of the temporal bone and the ear follows methods and techniques simulating, as far as possible, those employed in otological surgery, in postmortem gross examination, and in related histological examination of excised specimens. It is intended that the results should aid in the solution of problems that arise in the clinical care of the patient. This means that the investigation covers typical and variational anatomy, both normal and pathological; that it gives equal attention to both developmental and gross morphology. The embryological phase of the study, far from being a marginal aspect of little practical concern, is essential to an understanding of adult departure from the anatomic "normal". For example, the ossicles and the capsular wall of the labyrinthine systems retain, to a striking degree and throughout one's life span, the dimensions, histological architecture and relationships which were established in the fetus. In published reports emanating from this laboratory, an account of developmental anatomy introduces the condition encountered in the adult ear. Arrest in the succession of formative stops account for conditions that contribute to surgical risk. For the purpose of the present notice, it is important to record that parts of this investigation are periodically published in clinical journals, usually following presentation as papers on the programs of the American Otological Society, the Triological Society, the American Academy of Ophthalmology and Otolarynagology; and that, at various times, similar material appears in chapters of edited works and in single works of monographic nature.